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Note: These modules are based
on ZIF (Zero Intermediate
Frequency) technologies; when
performing EMC
(Electromagnetic Compatibility)
tests, there are no IF
(Intermediate Frequency)
components from the module to
consider.
Rev 1.12.6 Feb.10
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
Determining the antenna's location
Consider the following points when deciding where to put the
antenna:
Antenna location may affect RF performance. Although the
•
module is shielded to prevent interference in most applica‐
tions, the placement of the antenna is still very important —
if the host device is insufficiently shielded, high levels of
broadband or spurious noise can degrade the module's
performance.
Connecting cables between the module and the antenna
•
must have 50 impedance. If the impedance of the module
is mismatched, RF performance is reduced significantly.
Antenna cables should be routed, if possible, away from
•
noise sources (switching power supplies, LCD assemblies,
etc.). If the cables are near the noise sources, the noise may
be coupled into the RF cable and into the antenna.
Disabling the diversity antenna
MC57xx — I f your host device is not designed to use the
•
MC57xx module's diversity antenna, terminate the interface
with a 50 load.
MC8201 / M C8301V / M C8780 / M C8781 / M C8790 / M C8790V /
•
M C8791V / M C8792V / M C8795V / M C8700 — Use the AT
!RXDEN=0
command
!RXDEN=1
to enable receive diversity.
Interference and sensitivity
Several sources of interference can affect the RF performance
of the module (RF desense). Common sources include power
supply noise and device‐generated RF.
RF desense can be addressed through a combination of
mitigation techniques and radiated sensitivity measurement.
Power supply noise
Noise in the power supply can lead to noise in the RF signal.
Proprietary and Confidential
to disable receive diversity or
RF Integration
23
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